PARIS, July 3 (Reuters) - Sanofi sees a more diversified pipeline driving a return to growth at its diabetes unit in the coming years and will consider acquisitions and partnerships to help boost performance, a company executive said on Tuesday.

The French drugmaker's diabetes revenues have fallen since 2015, slumping some 11 percent last year alone, as its patent-expired Lantus insulin is being squeezed by pricing pressure in the United States, the world's-largest health market.

Analysts said the company had been slow to work on finding successors to Lantus and had underestimated competition.

"I will not commit to a new guidance for 2019 but we are clearly optimistic for the business," Stefan Oelrich, executive vice president for diabetes and cardiovascular at Sanofi, told Reuters.

He cited new drugs under development, the rising number of diabetes sufferers around the world and technological breakthroughs among his reasons for optimism.

The number of people with diabetes has risen from 108 million in 1980 to 422 million in 2014, according to the World Health Organisation.

Oelrich said the figure could climb up to 600 million in the next two decades. "We are facing an enormous unmet need in terms of medicines and solutions," he said of diabetes, pointing to areas of future demand such as China and the Middle East.

ALLIANCES

Sanofi currently sells eight diabetes drugs and has four others in development. The group is also working at improving its insulin pens and is building a diabetes management platform with U.S Verily Life Sciences, an Alphabet company.

Failure to maintain growth at one of Sanofi's main divisions and a struggle to find enough new molecules in other therapeutic areas over the past years to refill its pipeline led some investors to question the group's strategy.

Sanofi has partially addressed these concerns this year after it agreed to buy U.S haemophilia specialist Bioverativ for $11.6 billion and Belgium's Ablynx, which is developing an experimental drug for a rare blood disorder, for 3.9 billion euros ($4.54 billion).

Oelrich did not rule out future acquisitions in diabetes provided they were "a good fit".

New partnerships, along the lines of one signed in 2015 with German biotech firm Evotec, were also "possible", he said.

Sanofi and Evotec are aiming to develop cell-modulating diabetes therapies that could reduce or eliminate the need for insulin injections.

The French company has also teamed up in diabetes with South Korea's Hanmi and U.S Lexicon.